The present invention relates in general to ball joints for vehicles and in particular to a resilient compression member for such a ball joint which has a wear indicating mechanism formed integrally therewith.
Ball and socket type joints are well known mechanical devices which are frequently utilized in vehicle suspension and steering systems. Such joints are normally provided with an internal resilient mechanism, which generates preloading forces against selective components of the joint. The preloading forces urge and maintain those selected components in contact with the ball portion of the joint. As the components of the joint wear, vehicle springs external to the joint (which are typically connected to the ball portion thereof) generally prevent the ball and socket portions of the joint from developing a loose fit or "play" therebetween. The resilient mechanism maintains the selected components of the joint in contact with the ball portion, despite the relative movement thereof resulting from such wear. After a certain amount of use, however, excessive wear in the ball joint cannot be compensated for by the vehicle springs, and the joint must be removed from vehicle for service. Accordingly, it is desirable to monitor the amount of wear which has occurred within the ball joint during use in order to determine when service is necessary.
Since wear occurs to the internal components of the ball joint, it is difficult to determine how much wear has occurred therein without disassembling the joint for visual inspection or without elevating the associated wheel of the vehicle for manual manipulation. Obviously, such disassembly is undesirable, because it requires the removal of the joint from the vehicle at a time when such removal may not be necessary. As a result, wear indicating mechanisms have been developed which provide an external indication of the amount of internal wear within the joint, thus obviating the need for removal of the joint for inspection or for elevation of the wheel for manipulation. Unfortunately, known wear indicating mechanisms require the use of a number of additional parts, thereby increasing the cost of materials and assembly of the joint. Also, known wear indicating mechanisms have been prone to permitting leakage of lubricant from the joint.